(1) Field of the Invention
The present invention relates to the detackification of paints and the clarification of color-containing aqueous systems, and more particularly to the detackification of paints and the clarification of color-containing containing aqueous systems by the use of organic detackifiers.
(2) Description of the Related Art
The commercial application of primers and paints to articles such as vehicles, large appliances, large equipment, and other similar articles, is commonly carried out in paint spraying booths and with the use of automatic paint spraying apparatus. Large quantities of paints are applied at rapid rates and all paint that oversprays or drips from the target finally impacts some part of the paint booth or the painting apparatus, and must eventually be removed and disposed of.
Paint, as that term is used herein, includes a mixture of pigments and a fluid vehicle that provides a coating when applied to an appropriate surface. Paint encompasses a variety of water insoluble organic binder-containing coatings that are commonly applied by spraying operations. High solids, solvent-based base coats and clear coats are included, as are water-borne base and clear coats and solvent-borne and water-borne primers.
Typically, paint overspray is captured by a booth water wash stream which carries the paint to a sump where it is treated with a detackifier to convert it into a non-sticky sludge. The sludge can then be removed and disposed of and the water can be recycled to the spray booth.
Various methods have been reported for treating spray booth waters containing overspray paint, including the addition of compositions containing polymers and amphoteric metal salts which form insoluble hydroxides at pH levels above about 7.0. Such formulations are reported in, for example, U.S. Pat. Nos. 3,861,887, 3,990,986, 4,002,490, 4,130,674, and 4,440,647. U.S. Pat. No. 4,853,132 discloses the use of precipitates formed by the interaction of cationic polymers and inorganic anions to detackify solvent based paints.
U.S. Pat. No. 4,629,572 discloses the treatment of paint booth waste water with a blend of urea or aminotriazine-aldehyde polymers and water swellable clays. Another approach that was taught in U.S. Pat. No. 4,656,059 includes the use of melamine-formaldehyde polymers along with a surfactant (for paint dispersal) and a flocculant. JP 52071538 discloses the use of alum, polyaluminum chloride and calcium hydroxide in combination with polymer accelerators. U.S. Pat. No. 5,240,509 teaches the use of melamine-formaldehyde polymers in conjunction with an aluminum salt at pH values of 6.0 to 9.0.
U.S. Pat. No. 5,639,379 discloses the treatment of waste water effluent containing textile dyes with a permanganate salt, then hydrogen peroxide, followed by an inorganic coagulant (aluminum chlorohydrate) at basic pH and in the presence of an anionic organic coagulant. The clarification of low turbidity waters by the use of aniline-formaldehyde-polyamine polymers formed by a reaction having a formaldehyde:aniline ratio of at least 2, is disclosed in U.S. Pat. No. 4,422,944 to Selvarajan et al.
Mitchell, D. B., and G. A. Tonn, surveyed the use of inorganic and organic paint detackifiers in Organic Paint Detackifiers and Associated Benefits, presented at Water-Borne and Higher-Solids, and Powder Coatings Symposium, Feb. 26-28, 1992, New Orleans, La., sponsored by Dept. of Polymer Science, Univ. of Southern Miss., Hattiesburg, Miss., and Southern Society for Coatings Technology, pp. 610-625 (1992). Organic paint detackifiers that were discussed in that paper included mannich tannin, melamine formaldehyde resin, 1,3-phenylelediamine formaldehyde resin, 1,4-phenylelediamine formaldehyde resin, and aniline formaldehyde resin. The relative detackification performance of the last four of these materials was reported to be in the same order as they are listed above. Aniline formaldehyde resin was reported to provide poor detackification on all paint chemistries except two component polyurethanes, and its reduced efficacy compared to melamine formaldehyde resin was attributed to its limited insoluble surface area. No information was apparent regarding the composition of, or for the production or test conditions for any of the resins.
Despite the advances that have been made in the area of paint detackification and effluent water clarification, there remains a need for effective methods that can be used in different types of water treatment systems, such as for both paint detackification and clarification of effluent waters containing dyes, with a minimum amount of change or customization, and without the requirement of a number of additional components or of tedious and time-consuming monitoring and testing; there is also a need for such methods that require only relatively simple and inexpensive compounds; and there is also a need for methods of producing such compounds.
It is to these needs that the present invention is directed.
Briefly, therefore the present invention is directed to a novel method of clarifying an aqueous liquid comprising contacting the aqueous liquid with an effective amount of a polyarylamine polymer formed by the reaction of less than 2 moles of an aldehyde per mole of arylamine in the presence of an acid in an aqueous solution.
The present invention is also directed to a novel method for detackifying paint in an aqueous suspension comprising intermixing an effective amount of a polyarylamine polymer formed by the reaction of from about 0.5 to about 4 moles of an aldehyde per mole of an arylamine in the presence of an acid in an aqueous solution with the aqueous suspension comprising paint at a pH between about 5 and 14, thereby causing the paint to become detackified.
The present invention is also directed to a novel method for reducing the color content of a highly colored liquid comprising intermixing a highly colored liquid at a pH between about 0.1 and about 14 with an effective amount of a polyarylamine polymer formed by the reaction of from about 0.5 to about 4 moles of an aldehyde per mole of an arylamine in the presence of an acid in an aqueous solution.
The present invention is also directed to a novel composition for detackifying paint in an aqueous suspension comprising an aqueous mixture comprising a flocculant and/or a coagulant and a polyarylamine polymer formed by the reaction of less than 2 moles of an aldehyde per mole of arylamine in the presence of an acid in an aqueous solution.
The present invention is also directed to a novel composition for detackifying paint comprising an aqueous suspension of paint at a pH of greater than about 7, and an amount of a polyarylamine polymer that is sufficient to detackify the paint in the aqueous suspension and wherein the polyarylamine polymer is one that is formed by the reaction of less than 2 moles of an aldehyde per mole of arylamine in the presence of an acid in an aqueous solution.
The present invention is also directed to a novel method of producing a polyarylamine polymer that is suitable for detackifying paint and reducing the color content of highly colored liquids, the method comprising reacting less than 2 moles of aldehyde per mole of an arylamine in the presence of an acid to form a polyarylamine polymer.
The present invention is also directed to a novel method of reducing the color content of a highly colored liquid comprising contacting the liquid with an effective amount of a polyarylamine polymer formed by the reaction of from about 0.5 to about 4 moles of an aldehyde per mole of arylamine in the presence of an acid in an aqueous solution.
Among the several advantages found to be achieved by the present invention, therefore, may be noted the provision of an effective method that can be used in different types of water treatment systems, such as for both paint detackification and clarification of effluent waters containing dyes, with a minimum amount of change or customization; the provision of such methods that can be used without the requirement of a number of additional components or of tedious and time-consuming monitoring and testing; the provision of a method that requires only relatively simple and inexpensive compounds; the provision of compositions that contain can be used in such methods; and the provision of a method of producing such compounds.
In accordance with the present invention, it has been discovered that a novel polyarylamine polymer can be used to detackify paint in aqueous paint suspensions by contacting the paint suspension with an effective amount of the novel polymer, preferably at a basic pH. The novel polyarylamine is formed by reacting an aldehyde, such as formaldehyde, with an arylamine, such as aniline, in the presence of an acid in an aqueous solution. It has surprisingly been found that a particularly effective form of the polyarylamine can be produced when the molar ratio of the aldehyde to the arylamine in the reaction to produce the polyarylamine is less than 2. (As used herein, the molar ratio of aldehyde to arylamine can be expressed as aldehyde:arylamine.) This was unexpected, because the molar composition of the reactants leading to the production of a polyarylamine polymer was not previously known to have an effect upon the efficacy of the polymer in detackifying paint.
When the novel polyarylamine is added to a paint-containing waste water in an amount of from about 0.2 to about 0.3 g/g of paint, for example, it provides detackification results that are at least as good as, and often superior to, those produced by a commercial melamine formaldehyde resin used at the same levels.
In an alternative embodiment, the same polyarylamine can be used, often at an acidic pH, to reduce the color content of highly colored waste waters.
The subject polyarylamine polymer is formed by polymerizing an aromatic amine (which can be referred to herein as an xe2x80x9carylaminexe2x80x9d) with an aldehyde. The arylamine of the present invention can be any aromatic amine that is capable of reaction with an aldehyde to form a polymer. Useful arylamines include molecules wherein an amine group is bonded directly to a cyclic compound. It is preferred, but not required, that the cyclic compound is a benzene or benzenoid ring.
Preferred arylamines include anilines, substituted anilines such as alkylanilines, phenylenediamines, aminophenols, methylenedianiline and its homologues, and mixtures thereof. Particularly useful arylamines include aniline, toluidine, aminophenol, aminosalicylic acid, anthranilic acid, and sulfanilic acid. A particularly preferred arylamine is aniline.
The aldehyde that is useful in the present invention is any aldehyde that is capable of reacting with an arylamine to form a polyarylamine polymer. In general, useful aldehydes include any compound having the formula
R1xe2x80x94CHO 
where R1 is hydrogen or is an alkyl, aryl, alkylaryl, arylalkyl, arylamino, alkylamino, carboxyl, or aldehyde group.
Particularly useful aldehydes for the present invention include, without limitation, formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, crotonaldehyde, butyraldehyde, glyceraldehyde, glyoxylic acid, glyoxal, glutaraldehyde, and mixtures thereof. A preferred aldehyde is formaldehyde.
Alternatively, the aldehyde can be provided by an aldehyde releasing agent, such as, for example trioxane, polyoxymethylenes, paraformaldehyde and hexamethylenetetramine.
It is preferred that the polymerization of the arylamine and the aldehyde of the present method is carried out in the presence of an acid. It is believed that the acid acts as a catalyst and promoter for the reaction. Acids that can be used for this purpose include mineral and organic acids. Particularly useful acids include hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, acetic acid, glycolic acid, chloroacetic acid, citric acid. It is also possible to use mixtures of such acids. A particularly preferred acid is hydrochloric acid.
It is believed that the properties of the polyarylamine polymer can be modified by the inclusion of an amine that is in addition to, and is different than, the arylamine as a reactant in the polymerization reaction. However, the use of such materials is optional, and not required for the subject polyarylamine to be fully functional. In this specification, such an optional additional amine can be referred to as an xe2x80x9camine modifierxe2x80x9d. The amine modifier can be a primary amine, a secondary amine, an amide, an amidine, an imide, a polyamine, an aminoalcohol, an alkylenepolyamine, or a mixture of any of these. Preferred amine modifiers include methylamine, dimethylamine, benzylamine, ethylenediamine, phenylenediamines, aminophenols, diethylenetriamine, monoethanolamine, diethanolamine, fatty amines, dicyandiamide, melamine, urea and mixtures or combinations of any of these.
Particularly useful amine modifiers can include melamine, dicyandiamide, urea, diethylenetriamine, monoethanolamine and mixtures and combinations of these.
The arylamines, aldehydes, acids and amine modifiers of the present invention can be, but need not be, pure compounds and are most often materials having the standard purity and contaminant levels of such materials as are standard in the trade for commercial materials, or technical materials, of that name.
The condensation polymerization of an arylamine and an aldehyde is well known (See, e.g., U.S. Pat. No. 2,818,433, to Erickson et al., and Drumm et al., in Step-Growth Polymerizations, D. H. Solomon, Ed., pp. 262-263, Marcel-Dekker, Inc., New York (1972)). The general scheme of the reaction can be illustrated by the polymerization of aniline and formaldehyde, in the presence of an HCl catalyst, as shown by reactions I through IV, below: 
where R1 and R2 are independently hydrogen, or show a cross-linking or branching point in the polymer. It is believed that branching of the polymer can also occur from the nitrogen atoms.
The relative amounts of the arylamine and the aldehyde that are included as reactants in the polymerization reaction can range widely. However, because of the multiple potential reactions sites on an arylamine such as aniline, the aldehyde is rapidly consumed, and it is preferred that an amount of the aldehyde in excess of the stoichiometric amount required for straight chain polymerization be used in order to fully react all of the arylamine reactant. However, when the molar ratio of aldehyde-to-arylamine is increased, it is believed that polymer branching and cross-linking are promoted. If too much aldehyde is included, the resulting polymer will have excessive cross-linking. This can cause such undesirable characteristics as eventual gelation upon storage, even at ambient temperatures. It is also believed that the relative amounts of arylamine and aldehyde that are present for the polymerization reaction have an effect upon the molecular weight of the polymer and that this parameter also has an effect on the efficacy of the polymer in detackifying paints and clarifying highly colored waste waters.
The molar ratio of aldehyde:arylamine that is used for the reactants in the polymerization reaction of the subject method can vary widely, and can be almost any ratio that results in a polyarylamine product. However, it is preferred that the molar ratio of aldehyde:arylamine for the reactants in the polymerization reaction for the subject method is from about 0.5:1 to about 4:1, more preferably from about 0.5:1 to about 2:1, even more preferably to be less than 2:1, and yet more preferably to be from about 1.3:1 to about 1.7:1.
When an acid is included in the polymerization reaction as a catalyst, any amount of acid can be used that is sufficient to catalyze or accelerate the reaction. However, it is preferred that the ratio of the molar equivalents of acid to the moles of arylamine (which may be expressed herein as xe2x80x9cacid:arylaminexe2x80x9d) in the polymerization reaction for the subject method is from about 0.2:1 to about 3:1, more preferably from about 0.5:1 to about 1.2:1, and even more preferably from about 0.7:1 to about 1:1.
If an optional amine modifier is included as a reactant in the polymerization reaction of the subject method, it can be included at any level. It is believed to be preferred, however, that an amine modifier, if one is present, be present in a molar ratio of amine modifier:arylamine of from about 0:1 to about 10:1, more preferably in a molar ratio of from about 0:1 to about 1:1, and more preferably in a molar ratio of from about 0:1 to about 0.6:1.
When an amine modifier is included in the polymerization reaction, the aldehyde and acid usage can be calculated as described above, except that the term describing the moles of arylamine is replaced by a term describing the sum of the total moles of arylamine+amine modifier. For example, if an aldehyde:arylamine molar ratio of 1.6:1 is desired, then such ratio would be fulfilled by a reaction mixture comprising 1.6 moles of aldehyde and any combination of arylamine and amine modifier that totaled 1.0 mole.
Without being bound by this or any other theory, the inventors believe that for paint detackification, a large surface areaxe2x80x94thus, a small particle sizexe2x80x94of the precipitated subject polyarylamine is needed for best performance. Therefore, it is believed that a certain molecular weight and level of cross-linking are preferred in order to maximize (1) the number of particles and (2) the surface area for a given mass of the polymer. The preferred molecular weight is sufficiently high to cause precipitation under the conditions of use, but not so high as to cause gelation of the polymer during manufacture and transport. Similarly, cross-linking is believed to promote insolubilization and particle formation, but excessive cross-linking is also believed to cause gelation of the polymer. In the subject method for producing polyarylamines, the molecular weight and cross-linking levels are interdependent, so that one cannot be changed without influencing the other.
Mechanistically, cationic polymers have been reported to be very effective in paint detackification. See, e.g. Mitchell, D. B. and Tonn, G. A., Id. To verify this hypothesis, the inventors have synthesized and tested amphoteric polymers of anthranilic acid-formaldehyde, sulfanilic acid-formaldehyde, and 4-aminosalicylic acid-formaldehyde as detackifiers with poor results. The failure of these polymers was attributed to relatively high polymer solubility at a pH of 8.5 (the test condition), and to having inadequate cationic charge. Similarly, purely anionic polymers of phenol-formaldehyde and salicylic acid-formaldehyde, being completely soluble under the test conditions, did not show any activity at all.
Attempts to modify the aniline-formaldehyde polymers of the present invention by the incorporation of a co-reactant such as urea did afford stable polymers with good activity, as long as the molar ratio of urea/aniline was  less than 0.6.
Terpolymers of aniline-melamine-formaldehyde were also synthesized. However, it was found that because of limited water solubility of melamine, no more than 20 mole % melamine (based on aniline) could be incorporated into a stable terpolymer. No improvement in the detackification efficiency was noticed due to the presence of melamine in the polyarylamine polymer.
When aniline and formaldehyde are used as the arylamine and the aldehyde, other amines (the amine modifier) can be included in the polymer. The amine modifier can be a primary amine, such as methylamine or benzylamine, a secondary amine, such as dimethylamine, or N-methylaniline, a fatty amine, linear or branched alkyl or arylamines, guanidine, dicyandiamide, aminophenols, alkyl or aryl diamines such as ethylenediamine and phenylenediamines, or a polyamine such as diethylenetriamine. With such amines as these, at limited levels, polymerization could be realized by virtue of the amines being attached through the methylene bridges.
The polymerization of the arylamine and the aldehyde can be carried out by standard techniques. One suitable laboratory method involves charging a solution of water and the selected arylamine(s), such as aniline, into a glass polymerization flask equipped with a mechanical agitator, a condenser, an addition funnel, and a thermistor probe. Concentrated acid, such as hydrochloric acid, is added rapidly to the well-stirred aniline slurry and the clear solution of aniline hydrochloride is heated to 70xc2x0 C.-85xc2x0 C. After the mixture has reached this temperature, an aldehyde(s), such as formaldehyde, is added to the well-stirred mixture, whereupon a mild exotherm can be expected to raise the temperature of the mixture by 5xc2x0 C. to 10xc2x0 C. Heating is then resumed and the reaction temperature is maintained at about 100xc2x0 C. for 2-6 hours. The product solution of the polyarylamine polymer of the present invention can then be cooled and collected.
The order of addition and reaction time and temperature can be changed without departing from the scope of the invention. The polyarylamine may be subjected to post treatment to reduce the concentration of residual reactants such as the arylamine, the aldehyde, or the acid starting materials. The post treatment can include heating, purging with a gas, reacting the residual starting materials with a detoxifying or inactivating agent, evaporation or distillation under atmospheric or reduced pressure, or a combination of these methods.
The polyarylamine polymer can be stored and used as is from the aqueous solution in which it is synthesized, or it can be concentrated, separated, purified, adsorbed, and/or dried to form a solid material. It is preferred that the polyarylamine is provided for transportation, storage, and/or sale in an aqueous solution at a pH that is sufficiently low to maintain the polymer in solution. When the polymer is to be used to detackify paint or to clarify highly colored waste waters, the solution can be added to the spray booth water, or to any other solution where its activity is desired, and the pH of that waste water, or other solution, can then be adjusted to the pH that is preferred for best results in the subject method.
The subject polyarylamine polymer is water soluble under acidic conditions and is increasingly non-water soluble as the pH is increased.
When it is said that the subject polyarylamine is water soluble under acidic conditions, what is meant is that the polyarylamine is soluble in water in an amount of at least about 0.05% by weight at 25xc2x0 C. at a pH of 2. Preferably, it has a water solubility at 25xc2x0 C. of at least about 0.1% by weight at a pH of 2, more preferably a solubility of at least about 1% by weight at a pH of 2, and even more preferably, a solubility of at least about 2% by weight at a pH of 2. When it is said that the subject polyarylamine is non-water soluble under basic conditions, it is meant that the polyarylamine has a solubility in water at 25xc2x0 C. of less than about 0.05% at a pH of 12.
A preferred use for the subject polyarylamine is for paint detackification in painting operation waste waters. In this method, the polyarylamine is added to a waste water that contains, or is likely to be contacted with, or to contain, paint droplets or particles. The polyarylamine is added in an amount that is sufficient to cause the paint to become non-tacky, or non-sticky, to the extent necessary for the paint particles to be concentrated into a sludge that can be dewatered and handled. The paint sludge that has been treated with the subject polyarylamines can have a reduced tendency to stick to and foul surfaces with which it comes in contact, as compared with a paint sludge that has not been treated with the subject method. In standard paint-booth operations, it would be typical for the polyarylamine to be added to the paint-booth wash water as an emulsion or suspension and to be maintained in that water at some effective concentration. As the polyarylamine was attached to paint and removed from the wash water, additional polyarylamine could be added.
When the polyarylamine is used for paint detackification, it is believed to be advantageous that the polyarylamine not be present in the paint-booth wash water in the form of a true solution. Accordingly, it is common to maintain the spray booth wash water at a pH at which the polyarylamine is substantially non-water soluble. It is preferred that the waste water containing the paint is at a pH of from about 4 to about 14, when the polyarylamine is present. It is more preferred that the waste water be at a pH of from about 6 to about 12, and even more preferred that the waste water be at a pH of from about 7 to about 10, when the subject polyarylamine is present.
When the subject polyarylamine contacts the paint droplets, it causes the droplets to become less tacky and to become more easily dewatered. The dewatered paint sludge containing the subject polyarylamines is also more easily handled than a sludge in which the subject polyarylamines are not used. The paint sludge can be separated from the booth wash water, and the water can be recycled back to the booth.
The subject polyarylamines can also be used to treat solutions that contain solvents that are used for the cleaning of paint spray guns, paint lines, and other painting equipment. These cleaning solvents are known in the trade as xe2x80x9cpurge solventsxe2x80x9d. For such uses, the polyarylamine polymer preferably has the capability to cause the detackification of paint in the presence of purge solvents. After being used to clean painting equipment, the purge solvent contains some level of dispersed and/or dissolved paint, which can require detackification. Purge solvents generally contain a mixture of organic solvents. Alternatively, the purge solvent can be an aqueous emulsion of the organic solvents, optionally with surfactants and polymers. A common purge solvent mixture can include acetone, xylenes, ethylbenzene, trimethylbenzene, toluene, isopropanol and N-methylpyrrolidone.
The amount of the polyarylamine that is used for paint detackification can be from about 0.005 to about 10 grams of polyarylamine per gram of paint in the waste water. It is preferred that the polyarylamine is used in an amount of from about 0.03 to about 4 grams/gram of paint, more preferred in an amount of from 0.05 to 1 grams/gram of paint, and even more preferred in an amount of from 0.1-0.4 g of polyarylamine per gram of paint.
When the subject polyarylamine is added to a liquid for the purpose of paint detackification, it can be used alone, or it can be used to form a composition that also includes other detackifiers, flocculants, metal salts, metal hydroxides, coagulants, collectors, defoamers, surfactants, and the like. When another flocculant is used in such composition, such material can be an organic flocculant (cationic, anionic, nonionic, zwitterionic), such as polyvinylalcohol, styrene/acrylate copolymers, acrylate/acrylamide copolymers, cationic acrylamide copolymers, dicyandiamide/formaldehyde polymers, melamine/formaldehyde polymers, urea/formaldehyde polymers, epichlorohydrin/dimethylamine condensate, polyethylenimine, or poly(diallyldimethylammonium chloride). The polyarylamine can be used advantageously with inorganic metal oxides and salts such as alum, iron salts calcium carbonate, zirconium salts, aluminum hydroxide, titanium dioxide, silicates, silicas, and mixtures thereof. In particular, when the polyarylamine is present in such a composition in combination with an anionic or cationic flocculant, such materials as melamine/formaldehyde polymers, aluminum hydroxide, alum and mixtures and combinations of these can be used. The different additives can be added simultaneously or separately.
The subject polyarylamine has also been found to be particularly useful for coagulation and reducing the level of color-producing materials from non-paint containing liquids. The subject method can be used to reduce color in streams containing textile dyes, inks, colored effluents, papermill black liquors, lignins, lignosulfonates, humates, colloidal color bodies, and the like. It has also been found that the subject method is useful for reducing the color content of streams that occur as process streams or effluent streams from pulping processes, Bayer alumina processes and papermaking processes. Although the highly colored liquid can be aqueous, non-aqueous, or an aqueous/non-aqueous mixture, it is preferred that some water be present in the liquid. It is more preferred that the liquid be a predominantly aqueous liquid.
When it is said that the novel process may be used to xe2x80x9cclarifyxe2x80x9d such highly colored streams as are described above, it is meant that the process reduces the color content of such streams. However, this does not necessarily mean that the streams are cleared of all color after the subject treatment. The clarified stream may be clear, but it may also simply have less color than before treatment.
In this embodiment, the polyarylamine is generally added to the highly colored liquid when the liquid is maintained at a pH of from about 0.1 to about 14. It is preferred that the pH be maintained at a value of from about 0.1 to about 7, more preferred at a value of from about 2 to about 5, and even more preferred at a value of from about 3 to about 5. The polyarylamine can be mixed with the colored waste water by any known method, and the coagulated color bodies can be removed from the liquid by any of several commonly known methods, such as, for example, centrifugation, filtration, settling, dissolved air flotation, and the like.
When the subject polyarylamine is added to the aqueous liquid, it can be used alone, or it can be used in conjunction with other, known, materials, such as cationic or anionic coagulants, organic or inorganic coagulants, metal salts, metal hydroxides, organic flocculants (cationic, anionic, nonionic, or zwitterionic), and combinations of such materials, to form a composition. In particular, it is believed that a composition that includes the subject polyarylamines can also advantageously include poly(diallyldimethylammonium chloride) (DADMAC), epichlorohydrin/dimethylamine polymer, dicyandiamide/formaldehyde polymer, melamine/formaldehyde polymer, polyethyleneimine, alum, iron salts, and combinations of these. When the subject polyarylamine is used to form a composition that also includes one or more of these materials, the non-polyarylamine material can be added together with the polyarylamine, or the materials may be added separately.
The following examples describe preferred embodiments of the invention. Other embodiments within the scope of the claims herein will be apparent to one skilled in the art from consideration of the specification or practice of the invention as disclosed herein. It is intended that the specification, together with the examples, be considered to be exemplary only, with the scope and spirit of the invention being indicated by the claims which follow the examples.
In the examples all percentages are given on a weight basis unless otherwise indicated.
Aniline was provided in the form of a 99% pure liquid, and is available from Sigma-Aldrich, Milwaukee, Wis. It was used as received from the supplier.
Formaldehyde was provided in the form of a 37% solution in water, and is available from Sigma-Aldrich, Milwaukee, Wis. It was used as received from the supplier.
Concentrated hydrochloric acid was supplied as a 36.5%-38% solution of HCl in water and was used as supplied.
Examples 1-10 show the production of aniline-formaldehyde resins suitable for use in the method of the present invention.